As the world's supply of petroleum continues to diminish, it is ever more important that the maximum amount of petroleum be recovered from well sites. An important part of this effort involves improving telemetering relevant information from the subterranean environment to the surface, so that the petroleum industry can more efficiently drill wells and manage the production from those wells. In this invention, the word “communication” is used interchangeably with the word “telemetry,” and the word “data” is used interchangeably with the word “information.”
Currently, most down-hole telemetry is accomplished through systems based on mechanically pulsing the drilling fluid, or alternatively, wire or optical fiber circuits that are subject to abrasion and frequent breaks in the deleterious environment encountered in the well bore. Wire systems are subject to abrasion and cutting in the well bore environment, which can lead to communication failures due to inter-wire contact or an interruption of the communication circuit. Either failure condition may require that the communication circuit and assembly must be brought back to the surface for repair. Unreliability in down hole data is unfortunate for several reasons. Primarily, it is the high cost and loss of productive time associated with having the to raise a pipe string to fix a broken communication circuit. Additionally, reliable, real-time telemetry of data from the drill head can lead to increased efficiency of drilling and production operations.
The present invention presents apparatus and method for accomplishing reliable down hole communication. This is accomplished with minimal alteration of normal drilling equipment and procedures.